Bot position sensing

ABSTRACT

A storage and retrieval system including a storage structure having storage shelves, each storage shelf having slats for supporting stored items where the slats are spaced apart from each other by a predetermined distance, an autonomous transport vehicle including at least one sensor configured to sense each of the slats and output a signal indicating when a slat is sensed, and a controller for verifying a location of the autonomous transport vehicle within the storage structure based on at least the output signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/684,715, filed on Apr. 13, 2015, which is a continuation of U.S.patent application Ser. No. 13/327,035, filed on Dec. 15, 2011 (now U.S.Pat. No. 9,008,884), which is a non-provisional of and claims thebenefit of U.S. Provisional Patent Application No. 61/423,206 filed onDec. 15, 2010, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND

1. Field

The embodiments generally relate to storage and retrieval systems and,more particularly, to autonomous transports of the storage and retrievalsystems.

2. Brief Description of Related Developments

Warehouses for storing case units may generally comprise a series ofstorage racks that are accessible by transport devices such as, forexample, fork lifts, carts and elevators that are movable within aislesbetween or along the storage racks or by other lifting and transportingdevices. These transport devices may be automated or manually driven.Generally the items transported to/from and stored on the storage racksare contained in carriers, for example storage containers such as trays,totes or shipping cases, or on pallets.

When transporting the cases to and from the storage racks with automatedtransports it would be advantageous to be able to locate the automatedtransports relative to a case holding area for accurately picking andplacing cases to and from the case holding area.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the disclosed embodimentsare explained in the following description, taken in connection with theaccompanying drawings, wherein:

FIG. 1 schematically illustrates an exemplary storage and retrievalsystem in accordance with the embodiments;

FIG. 2 illustrates a schematic plan view of an exemplary storage andretrieval system in accordance with the embodiments;

FIG. 3 illustrates a structural portion of a storage and retrievalsystem in accordance with the embodiments;

FIGS. 4A and 4B illustrate storage shelves and an exemplary autonomoustransport vehicle in accordance with the embodiments;

FIG. 4C is a schematic illustration of an assembly jig in accordancewith the embodiments;

FIG. 5 is a schematic illustration of an autonomous transport vehicleand a portion of a storage shelf in accordance with the embodiments;

FIG. 6 is a schematic illustration of sensor output signals inaccordance with the embodiments;

FIG. 7 is a schematic illustration of a portion of a storage shelf andsensor beam in accordance with the embodiments;

FIG. 8 is a flow diagram in accordance with the embodiments;

FIG. 9 is a schematic illustration of an autonomous transport vehicleand a conveyor shelf in accordance with the embodiments;

FIG. 10 is a flow diagram in accordance with the embodiments;

FIG. 11 is a schematic illustration of an autonomous transport vehiclein accordance with the embodiments;

FIG. 12 is a schematic illustration of a portion of a storage shelf inaccordance with the embodiments;

FIG. 13 is a schematic illustration of a portion of the transportvehicle of FIG. 11 in accordance with the embodiments;

FIG. 14 is a schematic illustration of a portion of the transportvehicle of FIG. 11 in accordance with the embodiments;

FIG. 14A is a schematic illustration of a portion of a positioningsystem in accordance with the embodiments;

FIG. 15 is a flow diagram in accordance with the embodiments;

FIG. 16 is a schematic illustration of a portion of a picking aisle anda transport vehicle in accordance with the embodiments; and

FIG. 17 is a schematic illustration of a portion of the storage andretrieval system in accordance with the embodiments.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)

FIG. 1 schematically illustrates an exemplary storage and retrievalsystem in accordance with the embodiments. Although the disclosedembodiments will be described with reference to the embodiments shown inthe drawings, it should be understood that the disclosed embodiments canbe embodied in many alternate forms. In addition, any suitable size,shape or type of elements or materials could be used.

In accordance with the embodiments the storage and retrieval system 100may operate in a retail distribution center or warehouse to, forexample, fulfill orders received from retail stores for case units(where case units as used herein means items not stored in trays, ontotes or on pallets, e.g. uncontained or items stored in trays, totes oron pallets). It is noted that the case units may include cases of items(e.g. cases of soup cans, boxes of cereal, etc.) or individual itemsthat are adapted to be taken off of or placed on a pallet. In accordancewith the embodiments, shipping cases or case units (e.g. cartons,barrels, boxes, crates, jugs, totes, pallets or any other suitabledevice for holding case units) may have variable sizes and may be usedto hold items in shipping and may be configured so they are capable ofbeing palletized for shipping. It is noted that when, for example,bundles or pallets of case units arrive at the storage and retrievalsystem the content of each pallet may be uniform (e.g. each pallet holdsa predetermined number of the same item—one pallet holds soup andanother pallet holds cereal) and as pallets leave the storage andretrieval system the pallets may contain any suitable number andcombination of different items (e.g. each pallet may hold differenttypes of items—a pallet holds a combination of soup and cereal). Itshould be understood that the embodiments of the storage and retrievalsystem described herein may be applied to any environment in which caseunits are stored and retrieved.

The storage and retrieval system 100 may be configured for installationin, for example, existing warehouse structures or adapted to newwarehouse structures. In the embodiments, the storage and retrievalsystem may include in-feed and out-feed transfer stations 170, 160,multilevel vertical conveyors 150A, 150B, a storage structure 130, and anumber of autonomous transport vehicles or robots 110 (referred toherein as “bots”). The storage and retrieval system may also includerobot or bot transfer stations (as described in, for example, U.S.patent application Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVALSYSTEM” and filed on Apr. 9, 2010, the disclosure of which isincorporated by reference herein in its entirety) that may provide anindirect interface between the bots 110 and the multilevel verticalconveyor 150A, 150B. The in-feed transfer stations 170 and out-feedtransfer stations 160 may operate together with their respectivemultilevel vertical conveyors 150A, 150B for bi-directionallytransferring case units to and from one or more levels of the storagestructure 130. It is noted that while the multilevel vertical conveyorsare described herein as being dedicated inbound or in-feed conveyors150A and outbound or out-feed conveyors 150B, each of the conveyors150A, 150B may be used for both inbound and outbound transfer of caseunits/items from the storage and retrieval system. The multilevelvertical conveyors may be any suitable lifting devices for transportingcase units between levels of the storage and retrieval system. It isnoted that while multilevel vertical conveyors are described herein inother aspects the conveyors may be any suitable conveyors ortransfer/picking devices having any suitable transport path orientation.Some non-limiting suitable examples of multilevel vertical conveyors canbe found in, for example, U.S. patent application Ser. No. 13/327,088,entitled “MULTILEVEL VERTICAL CONVEYOR PLATFORM GUIDES” filed on Dec.15, 2011, and U.S. patent application Ser. No. 12/757,354, entitled“LIFT INTERFACE FOR STORAGE AND RETRIEVAL SYSTEMS” and filed on Apr. 9,2010 (the disclosures of which are incorporated by reference herein intheir entireties) and U.S. patent application Ser. No. 12/757,220,entitled “STORAGE AND RETRIEVAL SYSTEM,” (previously incorporated byreference). For example, the multilevel vertical conveyors may have anysuitable number of support shelves for transporting the case units to apredetermined level of the storage and retrieval system. The supportshelves may have slatted supports configured to allow fingers of thebots 110 or in-feed/out-feed transfer stations 170, 160 to pass betweenthe slats for transferring case units to and from the conveyor. It isnoted that in the embodiments transfer of case units between the botsand the multilevel vertical conveyors may occur in any suitable manner.

As may be realized, the storage and retrieval system 100 may includemultiple in-feed and out-feed multilevel vertical conveyors 150A, 150Bthat are accessible by, for example, bots 110 on each level of thestorage and retrieval system 100 so that one or more case unit(s) can betransferred from a multilevel vertical conveyor 150A, 150B to eachstorage space on a respective level and from each storage space to anyone of the multilevel vertical conveyors 150A, 150B on a respectivelevel. The bots 110 may be configured to transfer the case units betweenthe storage spaces and the multilevel vertical conveyors with one pick(e.g. substantially directly between the storage spaces and themultilevel vertical conveyors). By way of further example, thedesignated bot 110 picks the case unit(s) from a shelf of a multilevelvertical conveyor, transports the case unit(s) to a predeterminedstorage area of the storage structure 130 and places the case unit(s) inthe predetermined storage area (and vice versa).

The bots 110 may be configured to place case units, such as the abovedescribed retail merchandise, into picking stock in the one or morelevels of the storage structure 130 and then selectively retrieveordered items for shipping the ordered items to, for example, a store orother suitable location. In the embodiments, the bots 110 may interfacein any suitable manner with the multilevel vertical conveyors 150A, 150Bsuch as through, for example, extension of a transfer arm or effector110A (FIG. 9) of the bot (which may have fingers 110F (FIGS. 4A and 9))for interfacing with slatted support shelves of the multi-level verticalconveyors) relative to a frame of the bot. Suitable examples of bots aredescribed in U.S. patent application Ser. No. 12/757,312, entitled“AUTONOMOUS TRANSPORTS FOR STORAGE AND RETRIEVAL SYSTEMS” and filed onApr. 9, 2010, U.S. Provisional Patent Application entitled “BOT PAYLOADALIGNMENT AND SENSING” (Ser. No. 61/423,220) and filed on Dec. 15, 2010(now U.S. patent application Ser. No. 13/327,040 filed on Dec. 15,2011), U.S. Provisional Patent Application entitled “AUTOMATED BOT WITHTRANSFER ARM” (Ser. No. 61/423,365) and filed on Dec. 15, 2010 (now U.S.patent application Ser. No. 13/326,952 filed on Dec. 15, 2011), and U.S.Provisional Patent Application entitled “AUTOMATED BOT TRANSFER ARMDRIVE SYSTEM” (Ser. No. 61/423,388) and filed on Dec. 15, 2010 (now U.S.patent application Ser. No. 13/326,993 filed on Dec. 15, 2011), thedisclosures of which are incorporated by reference herein in theirentireties.

The storage structure 130 may include multiple levels of storage rackmodules where each level includes an array of storage spaces (arrayed onthe multiple levels and in multiple rows on each level), picking aisles130A formed between the rows of storage spaces, and transfer decks 130B.It is noted that the bots 110 may be configured to traverse the transferdecks 130B while being mechanically unconstrained and may be configuredto traverse the picking aisles 130A while being mechanically constrainedby, for example, rails or other guiding features located in the pickingaisles 130A. Any bot 110 traveling on a level of the storage structuremay enter any one of the picking aisles 130A located on that level whichmay allow for a variance between a frame of the bot 110 and targets orpositioning determining features 1201-1203 (FIG. 12) to exist. It isalso noted that each level may also include respective bot transferstations that provide an indirect interface between the bots and themultilevel vertical conveyors. In the embodiments, the picking aisles130A and transfer decks 130B may be arranged for allowing the bots 110to traverse respective levels of the storage structure 130 for placingcase units into picking stock and to retrieve the ordered case units. Asmay be realized, the storage and retrieval system may be configured toallow random accessibility to the storage spaces. For example, allstorage spaces in the storage structure 130 may be treated substantiallyequally when determining which storage spaces are to be used whenpicking and placing case units from/to the storage structure 130 suchthat any storage space of sufficient size can be used to store items.The storage structure 130 of the embodiments may also be arranged suchthat there is no vertical or horizontal array partitioning of thestorage structure. For example, each multilevel vertical conveyor 150A,150B is common to all storage spaces (e.g. the array of storage spaces)in the storage structure 130 such that any bot 110 can access eachstorage space and any multilevel vertical conveyor 150A, 150B canreceive case units from any storage space on any level so that themultiple levels in the array of storage spaces substantially act as asingle level (e.g. no vertical partitioning). The multilevel verticalconveyors 150A, 150B can also receive case units from any storage spaceon any level of the storage structure 130 (e.g. no horizontalpartitioning). It is noted that the storage and retrieval system may beconfigured so that each multilevel vertical conveyor serves apredetermined area of the array of storage spaces.

The storage structure 130 may also include charging stations 130C forreplenishing, for example, a battery pack of the bots 110. In theembodiments, the charging stations 130C may be located at, for example,transfer areas 295 (FIG. 2) of the transfer deck 130B so that the bots110 can substantially simultaneously transfer items, for example, to andfrom a multilevel vertical conveyor 150A, 150B while being charged. Thebots 110 and other suitable features of the storage and retrieval system100 may be controlled by, for example, one or more central systemcontrol computers (e.g. control server) 120 through, for example, anysuitable network 180. The network 180 may be a wired network, a wirelessnetwork or a combination of a wireless and wired network using anysuitable type and/or number of communication protocols. It is notedthat, in the embodiments, the system control server 120 may beconfigured to manage and coordinate the overall operation of the storageand retrieval system 100 and interface with, for example, a warehousemanagement system 125, which in turn manages the warehouse facility as awhole. The control server 120 may be substantially similar to thatdescribed in, for example, U.S. patent application Ser. No. 12/757,337,entitled “CONTROL SYSTEM FOR STORAGE AND RETRIEVAL SYSTEMS” and filed onApr. 9, 2010 (the disclosure of which is incorporated by referenceherein in its entirety).

Referring also to FIG. 2, an exemplary configuration of the storage andretrieval system 100 is shown. Other suitable exemplary configurationsof storage and retrieval systems can be found in, for example, U.S.patent application Ser. No. 12/757,381, entitled “STORAGE AND RETRIEVALSYSTEM” and filed on Apr. 9, 2010, and U.S. Provisional PatentApplication entitled “Warehousing Scalable Storage Structure” (Ser. No.61/423,340) and filed on Dec. 15, 2010 (now U.S. patent application Ser.No. 13/326,674 filed on Dec. 15, 2011), the disclosures of which areincorporated by reference herein in their entireties. It should beunderstood that the storage and retrieval system may have any suitableconfiguration. As can be seen in FIG. 2, the storage and retrievalsystem 200 is configured, for exemplary purposes only, as a single-endedpicking structure in which only one side of the system 200 has atransfer section or deck 130B. The single-ended picking structure may beused in, for example, a building or other structure having loading docksdisposed only on one side of the building. In this example, the storageand retrieval system 200 includes transfer deck(s) 130B and pickingaisles 130A that allow bots 110 to traverse an entirety of a level ofthe storage structure 130 on which that bot 110 is located fortransporting items between any suitable storage locations/picking aisles130A and any suitable multilevel vertical conveyors 150A, 150B. Themultilevel vertical conveyors 150A, 150B provide transport of case unitsinto the storage and retrieval system 200 through input workstations 210and provide output of case units from the storage and retrieval system200 through output workstations 220. In the embodiments, the storage andretrieval system 200 includes a first and second storage section 230A,230B located side by side so that the picking aisles of each section aresubstantially parallel with each other and facing the same direction(e.g. towards transfer deck 130B). It should be understood that in theembodiments the storage and retrieval system may have any suitablenumber of storage sections arranged relative to each other in anysuitable configuration.

Referring to FIGS. 1, 3, 4A and 4B, each of the storage bays 510, 511 ofthe storage structure 130 may hold the picking stock on storage shelves600 that are separated by aisle spaces 130A. In the embodiments thestorage bays 510, 511 and storage shelves 600 may be substantiallysimilar to those described in, for example, U.S. patent application Ser.No. 12/757,220, entitled “STORAGE AND RETRIEVAL SYSTEM,” and U.S. patentapplication Ser. No. 12/757,381, entitled “STORAGE AND RETRIEVAL SYSTEM”(both of which being previously incorporated by reference). For example,one or more support legs 620L1, 620L2 may be provided on the storageshelves 600 so that the support legs extend from, for example, thehorizontal supports 610, 611, 613 (which are supported by verticalsupports 612) (FIG. 8, Block 900). The support legs 620L1, 620L2 may beintegrally formed with the storage rack structure in any suitablemanner. For example, the support legs 620L1, 620L2 may have any suitableconfiguration and may be part of, for example, a substantially U-shapedchannel 620 such that the support legs 620L1, 620L2 are connected toeach other through channel portion 620B. The channel portion 620B mayprovide an attachment point between the channel 620 and one or morehorizontal supports 610, 611, 613. It should be understood that eachsupport leg 620L1, 620L2 may also be configured to individually mount tothe horizontal supports 610, 611, 613.

As may be realized, Referring also to FIG. 4C, the support legs 620L1,620L2 may be installed on the horizontal supports 610, 611, 613 with aninstallation jig 802. The installation jig 802 may include a body 800having a first set of grooves 801 configured so that the support legs620L1, 620L2, generally referred to as slats 620L, fit into the groovesfor accurately locating the slats 620L on the horizontal supports 610,611, 613 within a predetermined tolerance. The installation jig 802 mayinclude a second groove 803, substantially orthogonal to the first setof grooves 801. The second groove may be configured to accept a verticalsupport 612 for locating the installation jig 802 relative to thestorage rack structure. It should be understood that the installationjig 802 may be located relative to the storage rack structure in anysuitable manner for installing the slats 620L. The slats 620L may beaffixed to the storage structure in any suitable manner such as by, forexample, snaps, fasteners, welds, chemical bonding agents and the like.It should be understood that the slats 620L may be installed on thestorage rack structure in any suitable manner using any suitablealignment tools.

In the embodiments, each support leg 620L1, 620L2 includes a bentportion 620H1, 620H2 having a suitable surface area configured tosupport case units stored on the shelves 600. The bent portions 620H1,620H2 may be configured to substantially prevent deformation of the caseunits stored on the shelves. It should be understood that the legportions 620H1, 620H2 may have a suitable thickness or have any othersuitable shape and/or configuration for supporting case units stored onthe shelves. As can be seen in FIGS. 4A and 4B, the slats 620L orchannels 620 may form a slatted or corrugated shelf structure wherespaces 620S between, for example, the support legs 620L1, 620L2 allowfor arms or fingers 110F of the bots 110 to reach into the shelving fortransferring case units to and from the shelves as well as allowing thebot 110 to track its position within the storage rack structure. Theslats 620L may be mounted to the storage shelf 600 such that thedistance 620S (e.g. space between slats) places the slats 620L at knownincrements 130A for bot position location during picking and placingcase units to the storage shelves 600. In one example, the spacing 620Sbetween the slats 620L can be arranged to provide an incremental botpositioning system (e.g. the spacing 620S is substantially the samebetween all of the slats 620L where the bot location is tracked from abase or reference point such as an end of the picking aisle 130A). Inanother example, the spacing 620S between the support legs 620L1, 620L2can be arranged to provide an absolute bot positioning system (e.g. thespacing 620S follows a predetermined pattern so that each space whendetected by the bot provides a unique identifiable location of the botwithin the picking aisle) while still allowing the fingers 110F of thebot 110 to be inserted between the slats 620L for picking and placingcase units from the storage shelves 600. In the embodiments,substantially the same absolute encoder slat pattern may be used in eachof the picking aisles while in other alternate embodiments each of thepicking aisles may have a unique absolute encoder slat pattern so as toidentify the aisle as well as the bot location within the aisle. Itshould be understood that in the embodiments, the spacing between theslats 620L on the shelves 600 may be any suitable spacing to provide anysuitable measurement scale for determining the location of the bot suchas, for example, a combination of incremental and absolute positioningscales. The position of the bot may also be determined using a “map” or“fingerprint” of the cases on the storage shelves as will be describedin greater detail below. It is also noted that transfer of case units toand from the multilevel vertical conveyors 150A, 150B (whether thetransfer is made directly or indirectly by the bot 110) may occur in asubstantially similar manner to that described above with respect tostorage shelves 600.

Referring now to FIGS. 4A and 5, any suitable number of sensors fordetecting or sensing the slats 620L may be provided on the bot 110 (FIG.8, Block 910). In the embodiments the bot 110 includes two sensors 700,701 for exemplary purposes only. In the embodiments the sensors 700, 701are described as beam sensors including an emitter and a receiver. Theemitter and receiver of each sensor 700, 701 may be housed in a unitarysensor casing or separate sensor casings of the respective sensor 700,701. It should be understood that the sensors 700, 701 may be anysuitable types of sensors including, but not limited to, beam sensorsand proximity sensors such as magnetic sensors, capacitance sensors,inductance sensors and the like. The sensor 700 may be located towardsthe front of the bot 110 and the sensor 701 may be located towards therear of the bot 110. It should be realized that the terms “front” and“rear” are relative terms and used herein for exemplary purposes only asthe bot 110 may be configured to travel down the picking aisle 130A inany direction such that the front and rear of the bot, relative to thedirection of bot travel, may be reversed. It should be understood thatone or more sensors may be located at any suitable positions on the botsuch as for example, along any suitable length of any suitable side ofthe bot 110. The sensors 700, 701 may be mounted to the bot 110 in anysuitable manner such as to the chassis or any other portion of the bot110 structure.

The sensors 700, 701 may be mounted to the bot 110 for detecting orotherwise sensing the slats 620L to provide, for example, an incremental(or absolute) and discrete position encoder (FIG. 8, Block 920) fordetermining a location of the bot within, for example, a picking aisle130A or any other suitable location within the storage and retrievalsystem 100. The sensors 700, 701 may be mounted at any suitable angle θ(shown exaggerated in FIGS. 5, 7 and 9) relative to, for example, thebot chassis and/or the face 620LF of the slats 620L for generating asignal when a respective slat 620L is sensed. It is noted that the angleθ may allow, for example, a beam emitted from the sensor to be reflectedoff of, for example, the slats 620L and be received by a receiver of thesensor as will be described below. As may be realized, the emitter ofthe beam sensor may be configured such that the emitter is angledrelative to the sensor housing so that the housing can be mounted to thebot substantially parallel and/or perpendicular to one or morestructural features of the bot. As may also be realized where thesensors used are proximity sensors, the sensors may not be angled as theslats are detected through, for exemplary purposes only, changes incapacitance, inductance or magnetic fields as will be described ingreater detail below. It is noted that the sensors may have any suitablearrangement/configuration relative to the slats for detecting the slatsand determining a position of the bot. As a non-limiting example only,the back surface of the shelf may have an anti-reflective property thatallows the sensors to be placed so that the sensor beam of a reflectivetype sensor is substantially parallel to a longitudinal axis of theslats (e.g. not at an angle to the slats).

Referring also to FIG. 7, as the bot moves through the picking aisle130A in, for example, the direction of arrow 799 the beam 700B emittedfrom the emitter of sensor 700 strikes the side 620LS of the slat 620and is reflected away from the sensor (e.g. the beam is not returned tothe receiver of the sensor 700). As the bot continues to move in thedirection of arrow 799 the beam 700B strikes a face 620LF of the slat620L such that the beam 700B is reflected back to the receiver of sensor700 so that the sensor produces an output signal indicating the presenceof the slat 620L. During the continual movement of the bot 110 in thedirection of, for example, arrow 799 the beam 700B sweeps the face 620LFof the slat 620L such that the beam 700B continues to be reflected backto the receiver of sensor 700. As the receiver of sensor 700 receivesthe beam 700B the sensor 700 provides a substantially constant outputsignal to, for example, any suitable controller 1220 of the bot 110 (orstorage and retrieval system 100 such as control server 120). As the botcontinues to move in the direction of, for example, arrow 799 the beam700B moves off of the slat face 620LF and is no longer reflected back tothe receiver of the sensor 700 such that the sensor discontinues tooutput the substantially constant output signal to indicate no slat ispresent. As may be realized, as the bot moves past successive slats 620Lthe output signals (e.g. slat present, no slat present, slat present,etc.) generated by the sensor 700 may form of an “on/off” signal S700 asshown in FIG. 6 where the on/off output signals correspond to a pitch P(or spacing) of the slats (FIG. 8, Block 930). In this example, thesignal S700 is illustrated as a square wave but may have any suitablewaveform/shape. Sensor 701 may operate in the same manner as thatdescribed above with respect to sensor 700 such that the beam 701B fromsensor 701 is reflected off the slat faces 620LF to produce another“on/off” signal S701. As may be realized, the “on/off” signal may begenerated in a similar manner using proximity sensors where the signalis “on” when the slat is in proximity to the sensor (e.g. slat presenceis detected) and “off” when there is no slat presence detected.

The two signals S700, S701 generated by the respective sensors 700, 701form, for example, incremental encoder patterns (e.g. substantiallyequal pitch between slats) that may be interpreted by the controller1220 for determining a position of the bot within, for example, thepicking aisle 130A. It is noted that the pitch between slats may vary ina unique manner (while still allowing enough room for fingers 110F ofthe bot 110 to be inserted between the slats for picking and placingcase units from the storage shelves 600) to provide an absolute encoderpattern that can be interpreted by the controller 1220 for determiningthe location of the bot independent of previously detected slats of thepicking aisle 130A.

It is noted that the accuracy or resolution of the sensors 700, 701 maybe increased by, for example, placing the sensors 700, 701 on the bot110 such that the distance between sensors or the angle of the differentsensors results in at least one of the sensors being offset from theslat pitch P by a predetermined fractional amount to effectivelyincrease a number of slats detected by the bot for creating a finerresolution. For example, the distance L between sensors can be asfollows:L=mP+w,

where m is an integer and w is a predetermined fraction of the pitch P(e.g. P/2, P/4, . . . P/x). It is noted that the location of the slats620L within the storage shelves 600 may be located in a predeterminedconfiguration relative to, for example, the vertical supports 612 of thestorage structure. In one example, the vertical supports 612 may not beslatted and the higher position resolution may assist in confirming thebot location so that, for example, fingers 110F (FIG. 4A) of the bot 110do not contact the vertical supports 612 or support slats 612L whilepicking/placing case units from the storage shelves 600. In anotherexample, the vertical supports 612 may have false slats disposed thereonin a manner substantially similar to that described below with respectto the transfer areas 295 of the storage and retrieval system. In stillother examples, the bot position can be determined using RFID tags orbarcode labels mounted throughout the storage and retrieval structure.In this example the bot 110 may include any suitable RFID or barcodereader so that the RFID tags and/or barcodes can be read as the bot 110travels throughout the storage and retrieval system. In still otherexamples the location of the bot can be determined based on odometryinformation and feedback from the bot drive motors and their interactionwith the surface the bot rides on or against as will be described below.It should be understood that any suitable combination of the abovefeatures can be used to determine the location of the bot.

The controller 1220 of the bot 110 may have access to a storage andretrieval system structure file. The structure file may include thelocation of each structural feature of the storage and retrieval systemincluding the positions for each slat 620L within their respectivepicking aisles 130A. The structure file may be located in any suitablememory accessible by the controller 1220. In one example, the structurefile may be resident in a memory 1221 of the bot 110. In other examples,the structure file may be resident in a memory of, for example, thecontrol server 120 and accessed by the bot 110 or uploaded to a botmemory when the location of the bot 110 is being determined. The slatlocations specified by the structure file may assist in qualifying thelocation of the slats for determining the position of the bot 110within, for example, a picking aisle 130A. For example, when the botqualifies a slat such as slat 620L1 of the storage shelves 600 with oneof the sensors 700, 701 the controller 1220 of the bot compares anestimated location of the bot 110 using bot odometry (obtained from e.g.wheel encoders 720 as described below, which accounts for changes indiameter of the wheels due to, e.g. wear) at the instant in time whenthe slat 620L1 is detected with the location of the slat 620L1 asspecified by the information in the structure file (FIG. 8, Blocks 940and 950). If the comparison between the estimated bot location and thelocation of the slat from the structure file coincide within apredetermined tolerance the location of the bot (and the sensor sensingthe slat) is qualified with the slat such that the bot 110 knows itssubstantially exact location within the picking aisle 130A. It is notedthat the sensors 700, 701 may be located at a predetermined distancerelative to, for example, a location of an effector or arm 110A (FIG. 9)of the bot 110 so that the arm 110A can be positioned, based on thesensor's determined location relative to the storage slats 620L, forinserting fingers 110F of the arm 110A between the slats fortransferring containers between the bot 110 and the storage shelves 600.It is also noted that the controller 1220 may be configured to determinea state (acceleration, speed, direction, etc.) of the bot 110 as well asaccount for wheel slippage when determining the position of the botwithin the storage and retrieval system as described in, for example,U.S. Provisional Patent Application entitled “BOT HAVING HIGH SPEEDSTABILITY” and filed on Dec. 15, 2010 (now U.S. patent application Ser.No. 13/326,447 filed on Dec. 15, 2011), the disclosures of which areincorporated by reference herein in their entireties.

In the area between slats 620L1, 620L2 the bot 110 may be configured toobtain odometry information from wheel encoders 720 of the bot 110 tosubstantially continuously update an estimated position of the bot 110(e.g. by adding the distance traveled by the bot as determined from therotation of one or more of the bot's wheels to the bots last qualifiedposition or any other suitable previously determined position of thebot). The estimated position of the bot 110 may be based off of, forexample, the position of the last slat 620L1 detected and qualified(e.g. the location is verified through comparison with the structurefile) by the bot 110 (FIG. 8, Block 960). For example, when the bot 100encounters a subsequent slat 620L2 in the direction of travel 799through the picking aisle 130A the bot 110 calculates its estimatedposition using the verified position of the previously detected slat620L1 and the information from the wheel encoders 720. The bot 110compares this estimated position against the slat position informationcontained in the structure file for slat 620L2 and if the two locations(i.e. the bots estimated position and the position of the slat 620L2obtained from the structure file) coincide within the predeterminedtolerance then the bot 110 knows substantially exactly where it islocated within the picking aisle 130A and the bot's position within thepicking aisle 130A is updated by, for example, the bot controller 1220.If the estimated location of the bot 110 (when the sensor senses thesubsequent slat 620L2) is confirmed using the information in thestructure file then the slat/bot location is qualified. If there is nomatch or confirmation then the signal output from one or more of thesensors 700, 701 is ignored and the substantially exact position of thebot is not updated, rather the controller 1220 of the bot continues touse the estimated position obtained from the wheel encoders 720 untilthe location of a subsequently sensed slat is confirmed/qualified. It isnoted that in the embodiments, the bot odometry may be reset each time aslat position is qualified. The resetting of the bot odometry maysubstantially eliminate any built up tolerance or other cumulativetracking errors generated by, for example, the wheel encoders 720.Alternatively, the bot odometry may not be reset when each slat isqualified such that the bot controller or any other suitable controllerof the storage and retrieval system may be configured to account for anytolerance or cumulative tracking errors in the wheel encoders 720 whenqualifying the locations of the slats and determining a position of thebot.

Referring to FIGS. 2 and 9 a similar bot location system, such as thatdescribed above with respect to the location of the bot in the pickingaisle 130A may be used for determining the location of the bot 110relative to holding locations A, B on shelves of the multilevel verticalconveyors 150A, 150B. As can be seen in FIG. 9 each shelf 1000 of themultilevel vertical conveyors 150A, 150B may be configured to holdmultiple case units. In this example, two case units 1001, 1002 are heldon the conveyor shelf 1000 in holding areas A, B having a side by sidearrangement. The conveyor shelf 1000 is connected to a drive system soas to rotate around a predetermined path so that the shelf 1000 passesby the different levels of the storage and retrieval system fordelivering case units to the different levels as described in, forexample, U.S. patent application Ser. No. 12/757,354, entitled “LIFTINTERFACE FOR STORAGE AND RETRIEVAL SYSTEMS,” and U.S. patentapplication Ser. No. 12/757,220, entitled “STORAGE AND RETRIEVAL SYSTEM”(both previously incorporated herein by reference).

The storage and retrieval system is configured so that the bot cantravel into a transfer area 295 for transferring case units between thebot 110 and a holding area A, B of the conveyor shelf 1000. The transferarea 295 may have a wall 1100 or other suitable structure or surfaceconfigured to support, for example, any suitable number of false slats1620 (FIG. 10, Block 1500). The wall 1100 may be located between the bot110 and the conveyor shelf 1000 as the bot travels in the transfer area295. In the embodiments, the false slats 1620 may be substantiallysimilar to slats 620L but are merely mounted to the wall 1100 (ratherthan extend the depth of a storage shelf) and are not configured to holdor otherwise support case units. The false slats 1620 may be of anysufficient length (e.g. extend from the surface of the wall) to allowone or more sensors 700, 701 of the bot 110 (FIG. 10, Block 1510) todetect the false slats 1620. It should be understood that the falseslats may have any suitable configuration for, in the case of beamsensors 700, 701, reflecting the sensor beams 700B, 710B back to thesensors for locating the bot 110 relative to the holding locations A, Bof the conveyor shelf 1000 in a manner substantially similar to thatdescribed above. Where, for example, proximity sensors are used thefalse slats may have any suitable configuration for interacting with theproximity sensors. It should also be understood that the false slats1620 may have any suitable configuration for interacting with anysuitable sensors of the bot 110 for causing the sensors to output the“on/off” signal(s) described above.

While the false slats are illustrated in FIG. 9 as protruding from thewall 100, the false slats 1620 may be substantially flat surfacesconfigured to interact with the sensors 700, 701 in the manner describedherein. For example the wall or structure 1100 may have ananti-reflective surface on which reflective objects are mounted. Thereflective objects may be used in a manner substantially similar to thatof the false slats 1620 for interacting with the sensors 700, 701 andgenerating the on/off sensor signals S700, S701.

In operation, the bot 110 may receive instructions from, for example,the control server 120 to transfer a case unit, such as case unit 1001,1002, to or from the conveyor shelf 1000. The instructions may indicatewhich holding area A, B of the conveyor shelf 1000 the case unit islocated. The bot 110 may travel into a transfer area 295 correspondingto the conveyor shelf 1000 from/to which the bot 110 is to transfer acase unit. During travel in the transfer area 295, one or more sensors700, 701 of the bot 110 may sense or otherwise detect the false slats1620 in the manner described above with respect to slats 620L (FIG. 10,Block 1520). As each slat is detected an “on/off” signal, similar tosignals S700, S701 described above may be generated through sensoroutput (FIG. 10, Block 1530). The bot 110 may compare the location ofthe bot at the times the false slats 1620 are detected with, forexample, predetermined false slat locations within the storage andretrieval system structure file (FIG. 10, Block 1540). The position ofeach of the false slats 1620 may be correlated to a respective holdingposition A, B of the conveyor shelf 1000 such that if the false slatposition detected by the bot and the predetermined position match withina predetermined tolerance the bot knows substantially exactly where itis located within the transfer area 295 relative to the holding areas A,B of the conveyor shelf 1000 (FIG. 10, Block 1550). It is noted that thelocations of the false slats 1620 correspond to the location of thefingers 1000F of the conveyor shelf 1000 so that the fingers 110F of thebot arm 110A can be aligned between the false slots 1620 for extendingbetween the fingers 1000F without contact for picking/placing case unitsto the conveyor shelf 1000.

In a manner substantially similar to that described above, if the falseslat 1620 position detected by the bot 110 and the predeterminedposition of the false slats, as specified in the structure file, do notmatch within the predetermined tolerance the sensor signal correspondingto the detected false slat may be ignored. Where the number of falseslats or the length of the transfer area 295 does not allow for the bot110 to travel to another false slat for determining its position withinthe transfer area 295, the bot may change its travel direction so thatthe false slats 1620 can be re-detected by the bot 110. There may be a“starting false slat” that provides the bot 110 with an absoluteposition location within the storage structure. The starting false slatmay be located at a predetermined position within the transfer area 295such as at a beginning or entrance of the transfer area 295. If thebot's 110 position cannot be determined within the transfer area via thefalse slat detection, the bot may travel to the location of the“starting false slat” and re-detect the false slats 1620 in the mannerdescribed herein. The bot 110 may also obtain information from the wheelencoder(s) 720 for continually updating an estimate of its position in amanner similar to that described above (FIG. 10, Block 1560) when, forexample, the bot sensors are located between the false slats or if theposition of the bot 110 cannot otherwise be determined from the falseslats 1620.

In a manner similar to that described above, the false slats 1620 may bearranged to form an incremental or absolute encoding system fordetermining the location of the bot 110 relative to the holding areas A,B of the conveyor shelf so that the fingers 110F of the bot 110 can bealigned with a case unit, which in this example is case unit 1002, onthe conveyor shelf 1000. It is noted that, in one example, the falseslats 1620 may extend the length of the transfer area 295 while in otherexamples the false slats 1620 may be located only at the multilevelvertical conveyor access location (e.g. where the bot 110 stops toaccess the conveyor shelf 1000) of the transfer area 295. It is notedthat lines may be affixed or otherwise disposed on decks or othersuitable locations, such as the walls, of the transfer area 295 and/ormultilevel vertical conveyor access location. These lines may bedisposed transverse to the direction of bot travel at predeterminedlocations so that sensors on the bot 110 can detect the lines as the bottravels through the transfer area 295 and/or multilevel verticalconveyor access location for determining a position of the bot withinthe storage and retrieval system. It should be realized that the line orlines may alternatively be placed on the bottom or sides of the bot andsensors may be located on the deck or walls of the storage and retrievalsystem so that the sensor can detect the lines on the bot as the botpasses by the sensor for determining a location of the bot.

Referring again to FIG. 4 in the embodiments the bot 110 may alsoinclude one or more suitable case sensors 703, 704 configured forsensing case units 101 stored on the shelves 600. Some non-limitingexamples, of case unit sensors can be found in, for example, U.S. patentapplication Ser. No. 12/757,312, previously incorporated by referenceherein. In one example, the case sensors 703, 704 may include one ormore of a laser sensor and ultrasonic sensor. In another example, thecase sensors 703, 704 may be substantially similar to sensors 700, 701described above. The case sensors 703, 704 may be configured to allowthe bot 110 to sense each case unit 101 as the bot travels along apicking aisle. The case sensors 703, 704 may be connected to anysuitable controller such as, for example, control server 120 and/or botcontroller 1220 such that patterns or sequences of case units 101 may berecognized for assisting in a location determination of the bot 110. Forexample, the control server 120 may include a “map” or “fingerprint” ofcase units (including their respective sizes, positions, spacing betweenthe case units, etc.) for each picking aisle. As the bot 110 travelsthrough the picking aisle the controller, such as control server 120 (orbot controller 1220) may receive and interpret signals from the casesensors 703, 704 indicating, for example, the sizes and relativepositions of the case units 101 the bot is passing. The control server120, for example, may compare these signals with the case unitmap/fingerprint for determining, for example, which aisle the bot is inand which portion of the aisle the bot is in (e.g. the location of thebot within the aisle). In one example, as the bot 110 turns down apicking aisle the case units 101 may be sensed and the control server120 may determine if the bot 110 is in the correct aisle based on thesensed case units. It is noted that the fingerprint of cases may bedynamic as cases are added and removed from the shelves 600.

Referring to FIGS. 11-15, a bot location system using proximity sensorsfor determining the location of the bot in the picking aisle 130A and/orrelative to holding locations A, B on shelves of the multilevel verticalconveyors 150A, 150B is illustrated. In this aspect the bot 110 includesat least one proximity sensor module 1101 mounted to the frame of thebot (FIG. 15, Block 2500). The proximity sensor module 1101 may bemounted to the frame at any suitable location and for exemplary purposesis shown as being mounted to the frame below the payload holding area ofthe bot. Here the sensors are located on the bot as a position forsensing targets or position determining features 1201-1203 disposed onthe rails 1300 on which the bot travels through the picking aisles 130A(and/or on walls of the transfer area 295 and/or multilevel verticalconveyor access location—not shown—in a manner substantially similar tothat described above). In one aspect the proximity sensor module 1101includes a sensor mount 1101M that is movably mounted to the frame ofthe bot 110 in any suitable manner. In one example, the sensor mount1101M may be spring loaded or otherwise compliant such that the sensormount is slidably movable in the direction of arrow 1400 and biasedoutwards towards/against the rail 1300 (and/or walls of the transferarea 295 and/or multilevel vertical conveyor access location) as the bot110 moves through the picking aisles (or transfer areas/multilevelvertical conveyor access locations). In one aspect, the sensor mount1101M may have an integrally formed guide member 1101G that rides alongin substantial contact with the rail 1300 (e.g. the guide member is heldagainst the rail 1300 by the biasing force BF of the spring loadedmount) so that a substantially constant distance SX is maintainedbetween the targets 1201-1203 and the proximity sensor 11015 regardlessof position variance between the bot 110 frame and the targets. In otheraspects the guide member 1101G may be affixed or otherwise mounted tothe sensor mount 1101M in any suitable manner. The distance SX may beany suitable distance that allows the proximity sensor to sense thetargets 1201-1203. In one example, the distance SX may be about 2 mmwhile in other examples the distance SX may be more or less than about 2mm. The proximity sensor 11015 may be mounted or otherwise affixed tothe sensor mount 1101M in any suitable manner and may be any suitableproximity sensor (e.g. magnetic sensors, capacitance sensors, inductancesensors and the like). For exemplary purposes only the proximity sensormay be a Hall effect sensor. It is also noted that while only one sensormodule 1101 is shown on the bot 110 in other aspects there may be morethan one sensor module 1101 disposed at any suitable locations on thebot for sensing the targets 1201-1203.

As noted above, and referring to FIG. 12, the targets 1201-1203 may beprovided on the rails 1300 of the picking aisles and/or walls of thetransfer area 295 and/or multilevel vertical conveyor access location(FIG. 15, Block 2510). In one aspect, the targets 1201-1203 may beprovided on the rails on both sides of the picking aisle 130A so thatthe proximity sensor 1101 of the bot may determine its position withinthe picking aisle by sensing the targets regardless of which travelorientation the bot enters the picking aisle to allow the bot to pickfrom both sides of the aisle. In other aspects the targets may beprovided on but one side of the picking aisle and at least one proximitysensor module 1101 may be disposed on both lateral sides 11051, 110S2 ofthe bot so that the targets on but one side of the aisle can be sensedby the proximity sensors of the bot regardless of the travel orientationof the bot for allowing the bot to pick from both sides of the aisle. Asmay be realized the targets 1201-1203 may be located on rails in areference frame of the storage shelf or storage shelf area. For example,the targets 1201-1203 may have a predetermined relationship with theslats 620L1, 620L2 or other any other suitable feature of the storageshelf (such as when the storage shelf is configured without slats orotherwise). The targets 1201-1203 may be integrally formed with therails 1300 or otherwise mounted to or affixed to the rails 1300 in anysuitable manner. In one aspect the targets 1201-1203 may be formed inthe rails 1300 during manufacture of the rails 1300. The targets1201-1203 may have any suitable configuration that allows the targets tobe sensed or otherwise detected by the proximity sensor 1101 of the bot110. For exemplary purposes only, in one aspect the targets 1201-1203may be apertures, such as e.g. slots or holes, or recesses provided in aside wall 1300B of the rails 1300. Also for exemplary purposes only, theslots may be about 6 mm wide by about 12 mm tall slots or slots havingany other suitable dimensions. In other aspects the targets 1201-1203may be any suitable target for influencing the proximity sensor 1101 toproduce an on/off signal as will be described below. The targets1201-1203 may be provided in the rails 1300 at predetermined spacedintervals (e.g. the distances between the targets and the location ofeach target is known) so that the targets 1201-1203, along with theproximity sensor 1101, form an incremental (or absolute) and discreteposition encoder for determining a location of the bot within, forexample, a picking aisle 130A or any other suitable location within thestorage and retrieval system 100. In one aspect the targets 1201-1203may be spaced about 0.3048 m (about 1 ft) from each other. In otheraspects the targets 1201-1203 may be spaced by a distance that is moreor less than about 0.3048 m. In still other aspects the targets1201-1203 may have a varied spacing between the targets that providesfor an absolute position determination within, for example, a pickingaisle or any other suitable location of the storage structure.

As noted above the targets 1201-1203 may also be disposed at walls ofthe transfer area 295 and/or multilevel vertical conveyor accesslocation. In a manner substantially similar to that described above, thetargets 1201-1203 may be integrally formed in the walls of the transferarea 295 and/or multilevel vertical conveyor access location orotherwise affixed in any suitable manner to the walls. The targets1201-1203 at the transfer area 295 and/or multilevel vertical conveyoraccess location may be located on the walls in a reference frame of arespective one of the transfer area 295 and/or multilevel verticalconveyor so that the targets 1201-1203 have a predetermined relationshipwith, for example, a shelf of the multilevel vertical conveyor or anyother reference point at the transfer station or of the multilevelvertical conveyor in a manner substantially similar to that describedabove with respect to the picking aisles.

In a manner similar to that described above, the controller 1220 of thebot 110 may have access to a storage and retrieval system structurefile. The structure file may include the location of each structuralfeature of the storage and retrieval system including the positions foreach target 1201-1203 within their respective picking aisles 130A. Thetarget 1201-1203 locations specified by the structure file may assist inqualifying the location of the targets for determining the position ofthe bot 110 within, for example, a picking aisle 130A. For example, asthe bot travels along, for example, a picking aisle the bot 110 sensesthe targets 1201-1203 (FIG. 15, Block 2520) with the proximity sensormodule 1101 such that the proximity sensor module 1101 produces anon/off signal (FIG. 15, Block 2530) in a manner substantially similar tothat described above. The bot 110 qualifies the target(s) 1201-1203 ofthe rail 1300 with the proximity sensors 1101 where the controller 1220of the bot compares an estimated location of the bot 110 using botodometry (obtained from e.g. wheel encoders 720 in a mannersubstantially similar to that described above) at the instant in timewhen the target 1201-1203 is sensed with the location of the target1201-1203 as specified by the information in the structure file (FIG.15, Block 2540). If the comparison between the estimated bot locationand the location of the target 1201-1203 from the structure filecoincide within a predetermined tolerance the location of the bot (andthe sensor sensing the slat) is qualified (FIG. 15, Block 2550) with thetarget 1201-1203 such that the bot 110 knows its substantially exactlocation within the picking aisle 130A.

In a manner substantially similar to that described above, in the areabetween targets 1201-1203 the bot 110 may be configured to obtainodometry information from wheel encoders 720 of the bot 110 tosubstantially continuously update an estimated position of the bot 110(e.g. by adding the distance traveled by the bot as determined from therotation of one or more of the bot's wheels to the bots last qualifiedposition or any other suitable previously determined position of thebot) for updating a position of the bot 110 with the wheel encoders(FIG. 15, Block 2560). For example, the estimated position of the bot110 in the area between targets 1201-1203 may be based off of, forexample, the position of the last target 1201-1203 detected andqualified (e.g. the location is verified through comparison with thestructure file) in a manner substantially similar to that describedabove. The bot odometry may be used to align the fingers 110F of the arm110A with the slats for transferring containers between the bot 110 andthe storage shelf 600.

It is noted that, the positioning of the bot within, for example, thepicking aisles 130A may be decoupled from the structure of the storageshelves 600. For example, if the slats 620L1, 620L2 become deformed orbent this deformation will have substantially no impact on the locationdetermination of the bot within the picking aisles as the targets1201-1203 being sensed by the proximity sensor 11015 are disposed on therails 1300. This allows for the modification and/or replacement of theslats 620L1, 620L2 without substantially impacting the ability of thebot to determine its location within the storage and retrieval system.As may be realized, in one aspect, there may be some correlation betweenthe targets 1201-1203 and the slats 620L1, 620L2 to allow for insertingfingers 110F of the arm 110A between the slats for transferringcontainers between the bot 110 and the storage shelves 600. In otheraspects the bot 110 may include any suitable sensors, such as thosedescribed above, for detecting the positions of the slats to allow forinserting fingers 110F of the arm 110A between the slats fortransferring containers between the bot 110 and the storage shelves 600.

Referring now to FIG. 16, in one aspect of the disclosed embodiment, thebeam sensors 700, 701 described above with respect to FIGS. 4A-10 may bepositioned on the frame of the bot below the payload carrying area in amanner substantially similar to the proximity sensor 1101. The sensors700, 701 may be positioned to sense the targets 1201-1203 on the rails1300 so that as each target 1201-1203 is sensed by a respective sensor700, 701 that sensor produces an on/off signal in a manner substantiallysimilar to that described above with respect to the slat detection fordetermining a position of the bot in a manner substantially similar tothat described above. As may be realized, the bot may have sensors 700,701 on both lateral sides of the bot 11051, 110S2 so that the sensors700, 701 may detect the targets 1201-1203 regardless of the travelorientation of the bot where the targets 1201-1203 are located on butone rail 1300 in the picking aisle 130A.

In other aspects the bot 110 may include both the beam sensors 700, 701and one or more proximity sensors 1101 that are used in conjunction witheach other for determining a position of the bot within the storagestructure. In one aspect the proximity sensors 1101 may be used todetermine a location of the bot within the picking aisle 130A while thebeam sensors 700, 701 may be used to determine a location of the bot inan area between the targets 1201-1203 for aligning the arm 110A of thebot with the slats on the storage shelf 600 for transferring containersbetween the bot 110 and the shelf 600. In other aspects the beam sensors700, 701 and proximity sensors 1101 may be used in any suitable mannerfor determining a location of the bot within the storage structure andfor transferring containers between the bot 100 and the storage shelves600.

Referring now to FIG. 17 the storage and retrieval system may alsoinclude a bot location system for locating the bot upon, for example,initialization of the bot and during, for example, travel of the botalong the transfer deck 130B. In one aspect, the bot location system mayuse radio waves for determining a location of the bot and include anysuitable number of transmitters and receivers. In other aspects the botlocation system may use any suitable devices capable of allowing for aposition determination of the bot such as, for example, opticaltransmitters and receivers and acoustic transmitter and receivers. Inone aspect radio device 2600, such as transponders, transceivers,transmitters, etc., may be placed at any suitable locations within thestorage structure on, for example, the vertical 612 or horizontal 610,611 (FIG. 3) supports of the storage structure. For exemplary purposes,the radio devices 2600 may be placed at the intersection between eachpicking aisle 130A and the transfer deck 130B and at each storage bay510, 511 of the picking aisles 130A. In one aspect the radio devices2600 may be passive radio devices such as radio frequency identification(RFID) tags while in other aspects the radio devices may be activedevices. Where the radio devices 2600 are passive the bot 110 mayinclude a transceiver and antenna 110AN that is configured tocommunicate with and energize the transponders 2600 for receivinginformation stored in the transponders 2600. The information stored inthe transponders may include a storage aisle identification, a storagebay identification, a multilevel vertical conveyor location, transferdeck location and/or any other location information pertaining to alocation within the storage structure. The bot 110 may be configured tointerrogate the radio devices 2600 at any suitable times during theoperation of the bot such as when travelling through the storagestructure or upon initialization (e.g. turning on) of the bot 110. Inone aspect when a bot 110 is initialized within the storage structurethe bot 110 may interrogate one or more nearby radio devices 2600 andreceive position information from the devices 2600 as to where the botis located. In the example, shown in FIG. 17 the bot 110 may receiveinformation from radio devices 2600A, 2600B that is processed by, forexample, controller 1220 indicating the bot is located in aisle 130A1between bays 510 and 511. This position information may provide aninitial location of the bot 110 that may be supplemented and refined byposition information received from one or more of the sensors 700, 701,1101. In other aspects, the radio devices 2600 may be interrogated bythe bot 110 while the bot 110 is moving at substantially high speedsalong the transfer deck and picking aisles such that when the bot 110receives position information from the radio devices 2600 that the bot100 is located at a predetermined location the bot may slow down andobtain position information from one or more of the sensors 700, 701,1101. As may be realized, the radio devices 2600 and the transceiver andantenna 110AN may also be used to obtain a position of the bot 110 withany desired accuracy such as through any suitable analysis of thesignals received from the radio devices 2600 that may or may not besupplemented by position information obtained from sensors 700, 701,1101.

In a first aspect of the disclosed embodiment a storage and retrievalsystem is provided. The storage and retrieval system includes a storagestructure having storage shelves, each storage shelf having slats forsupporting stored items where the slats are spaced apart from each otherby a predetermined distance. An autonomous transport vehicle is alsoprovided where the autonomous transport vehicle includes at least onesensor configured to sense each of the slats and output a signalindicating when a slat is sensed. A controller is provided for verifyinga location of the autonomous transport vehicle within the storagestructure based on at least the output signal.

In accordance with a first sub-aspect of the first aspect of thedisclosed embodiment the controller is configured to compare a locationof the autonomous transport vehicle at a time the slat is sensed with apredetermined location of the slat and updating a verified location ofthe autonomous transport vehicle if the locations substantiallycoincide.

In accordance with the first sub-aspect of the first aspect of thedisclosed embodiment, the controller is configured to ignore the outputsignal of the at least one sensor where the locations do notsubstantially coincide.

In accordance with a second sub-aspect of the first aspect of thedisclosed embodiment, the controller is configured to continuouslyupdate an estimated location of the autonomous transport vehicle basedon a last known verified location of the autonomous transport vehicle.

In accordance with the second sub-aspect of the first aspect of thedisclosed embodiment, the autonomous transport vehicle includes at leastone wheel encoder and the controller is configured to obtain wheelencoder information for updating the estimated location of theautonomous transport vehicle.

In accordance with a third sub-aspect of the first aspect of thedisclosed embodiment the autonomous transport vehicle is configured toalign transfer arm fingers of the autonomous transport vehicle withspaces located between the slats of a respective storage shelf based onthe determined location of the autonomous transport vehicle forextending the transfer arm fingers into the spaces without contactingthe slats.

In accordance with the first aspect of the disclosed embodiment theautonomous transport vehicle includes a case unit detection sensorconfigured for detecting case units located on the storage shelf and thecontroller is configured to determine a position of the autonomoustransport vehicle based on the sensed case units.

In accordance with a second aspect of the disclosed embodiment, astorage and retrieval system is provided. The storage and retrievalsystem includes at least one multilevel vertical conveyor having atleast one shelf having support finger. At least one wall is alsoprovided adjacent the multilevel vertical conveyor, the wall includingprotrusions substantially aligned with the support fingers. Anautonomous transport vehicle is provided where the autonomous transportvehicle includes at least one sensor configured to sense each of theprotrusions and output a signal indicating when a protrusion is sensed.A controller is provided and is configured to determine a location ofthe autonomous transport vehicle relative to the support fingers basedon the output signal from the at least one sensor.

In accordance with the second aspect of the disclosed embodiment theautonomous transport vehicle includes a transfer arm having transferfingers, the autonomous transport vehicle being configured to align thetransfer arm fingers with spaces located between the support fingers ofthe at least one shelf based on the determined location of theautonomous transport vehicle for extending the transfer arm fingers intoa path of the shelf without substantial contact with the supportingfingers.

In accordance with the second aspect of the disclosed embodiment, the atleast one shelf includes at least two item holding locations and theautonomous transport vehicle includes a transfer arm, the autonomoustransport vehicle being configured to align the transfer arm with one ofthe at least two item holding locations based on the output signal fromthe at least one sensor.

In accordance with a third aspect of the disclosed embodiment an encoderfor determining a position of an autonomous transport vehicle isprovided. The encoder includes at least one slat mounted adjacent atravel lane of the autonomous transport vehicle, at least one sensormounted on the at least one autonomous transport vehicle where the atleast one sensor is configured to sense the at least one slat and outputa presence signal when each of the at least one slat is sensed, and acontroller configured to receive the presence signal and determine alocation of the autonomous transport vehicle along the travel path basedon the presence signal.

In accordance with the third aspect of the disclosed embodiment, the atleast one slat comprises item supports of a storage shelf.

In accordance with the third aspect of the disclosed embodiment, the atleast one slat comprises a protrusion mounted on a wall adjacent thetravel lane.

In accordance with the third aspect of the disclosed embodiment, the atleast one sensor comprises at least one of a beam sensor and a proximitysensor.

In accordance with the third aspect of the disclosed embodiment, whereineach of the at least one slats are spaced from each other by apredetermined pitch and a distance between each of the at least onesensors are spaced apart from each other by a fractional portion of thepitch.

In accordance with the third aspect of the disclosed embodiment, the atleast one sensor is angled relative to a face of the at least one slat.

In accordance with the third aspect of the disclosed embodiment, aspacing between each of the at least one slats effects an incrementaldetermination of the location of the autonomous transport vehicle.

In accordance with the third aspect of the disclosed embodiment, aspacing between each of the at least one slats effects an absolutedetermination of the location of the autonomous transport vehicle.

In accordance with a first sub-aspect of the third aspect of thedisclosed embodiment, the controller is configured to compare a locationof the autonomous transport vehicle at the time a slat is sensed with apredetermined location of the sensed slat for verifying the location ofthe autonomous transport vehicle.

In accordance with the first sub-aspect of the third aspect of thedisclosed embodiment, the controller is configured to update a locationof the autonomous transport vehicle when the location of the autonomoustransport vehicle at the time a slat is sensed and the predeterminedlocation of the sensed slat coincide.

In accordance with the first sub-aspect of the third aspect of thedisclosed embodiment, the controller is configured to ignore thepresence signal generated when the location of the autonomous transportvehicle at the time a slat is sensed and the predetermined location ofthe sensed slat do not coincide.

In accordance with the third aspect of the disclosed embodiment, theautonomous transport vehicle includes at least one wheel encoder, thecontroller being configured to obtain information from the wheel encoderand determine an estimated location of the autonomous transport vehiclefrom the wheel encoder information and based on a previously determinedlocation of the autonomous transport vehicle.

In accordance with a fourth aspect of the disclosed embodiment, astorage and retrieval system is provided. The storage and retrievalsystem includes a storage shelf structure having stationary positioningdetermining features with respect to a reference feature of the storageshelf structure where the positioning determining features are spacedapart from each other by a predetermined distance, an autonomoustransport vehicle including at least one sensor configured to sense eachof the positioning determining features and output a signal when atarget is sensed as the autonomous transport vehicle moves past thepositioning determining features, where the bot is configured for bothmechanically constrained travel and mechanically unconstrained travel,and a controller configured to verify a location of the autonomoustransport vehicle relative to the storage shelf structure based on atleast the output signal.

In accordance with a fourth aspect of the disclosed embodiment, thetargets include slats forming part of the storage shelf structure andconfigured to support stored items on the storage shelf structure.

In accordance with a first sub-aspect of the fourth aspect of thedisclosed embodiment, the storage and retrieval system further includesrails disposed in picking aisles and configured to mechanicallyconstrain travel of the autonomous transport vehicle and to provideaccess to the storage shelves wherein the positioning determiningfeatures include apertures formed in the rails.

In accordance with the first sub-aspect of the fourth aspect of thedisclosed embodiment, the positioning determining features are ofunitary construction with the storage shelf structure that defines thepositioning determining features.

In accordance with the fourth aspect of the disclosed embodiment, the atleast one sensor includes an optical sensor.

In accordance with the fourth aspect of the disclosed embodiment, the atleast one sensor includes a proximity sensor.

In accordance with the fourth aspect of the disclosed embodiment, the atleast one sensor includes a Hall effect sensor.

In accordance with a second sub-aspect of the fourth aspect of thedisclosed embodiment, the positioning determining features include radiodevices disposed at predetermined locations on supports of the storagestructure and the at least one sensor includes at least an antenna forinterrogating the radio devices and obtaining information regarding apredetermined location of an interrogated radio device.

In accordance with the second sub-aspect of the fourth aspect of thedisclosed embodiment, the positioning determining features and at leastthe antenna are configured to provide a position of the autonomoustransport vehicle upon an initialization of the autonomous transportvehicle.

In accordance with the fourth aspect of the disclosed embodiment, thesensor is movably mounted to the autonomous transport vehicle and biasedtowards the stationary positioning determining features.

It should be understood that the exemplary embodiments disclosed hereincan be used individually or in any suitable combination thereof. Itshould also be understood that the foregoing description is onlyillustrative of the embodiments. Various alternatives and modificationscan be devised by those skilled in the art without departing from theembodiments. Accordingly, the present embodiments are intended toembrace all such alternatives, modifications and variances that fallwithin the scope of the appended claims.

What is claimed is:
 1. A storage and retrieval system comprising: astorage structure having storage shelves, each storage shelf havingreference datums integrally formed with the storage shelves and beingspaced apart from each other by a predetermined distance; an autonomoustransport vehicle including at least one sensor configured to sense eachof the reference datums and output a signal indicating when a referencedatum is sensed; and a controller for verifying a location of theautonomous transport vehicle within the storage structure based on atleast the output signal and configured to compare a location of theautonomous transport vehicle at a time the reference datum is sensedwith a predetermined location of the reference datum and updating averified location of the autonomous transport vehicle if the locationssubstantially coincide.
 2. The storage and retrieval system of claim 1,wherein the controller is further configured to ignore the output signalof the at least one sensor where the locations do not substantiallycoincide.
 3. The storage and retrieval system of claim 1, wherein thecontroller is configured to continuously update an estimated location ofthe autonomous transport vehicle based on a last known verified locationof the autonomous transport vehicle.
 4. The storage and retrieval systemof claim 3, wherein the autonomous transport vehicle includes at leastone wheel encoder and the controller is further configured to obtainwheel encoder information for updating the estimated location of theautonomous transport vehicle.
 5. The storage and retrieval system ofclaim 1, wherein the autonomous transport vehicle is configured to aligntransfer arm fingers of the autonomous transport vehicle with spaceslocated between the reference datums of a respective storage shelf basedon the determined location of the autonomous transport vehicle forextending the transfer arm fingers into the spaces without contactingthe reference datums.
 6. The storage and retrieval system of claim 1,wherein the autonomous transport vehicle includes a case unit detectionsensor configured to detect case units located on the storage shelf andthe controller is further configured to determine a position of theautonomous transport vehicle based on the sensed case units.
 7. Thestorage and retrieval system of claim 1, wherein the reference datumsare configured to support case units stored on a respective storageshelf.
 8. A method comprising: providing a storage structure havingstorage shelves; providing each storage shelf with reference datums thatare integrally formed with the storage shelves and spaced apart fromeach other by a predetermined distance; sensing each of the referencedatums with at least one sensor of an autonomous transport vehicle andoutputting a signal indicating when a reference datum is sensed;verifying, with a controller, a location of the autonomous transportvehicle within the storage structure based on at least the output signaland comparing a location of the autonomous transport vehicle at a timethe reference datum is sensed with a predetermined location of thereference datum and updating a verified location of the autonomoustransport vehicle if the locations substantially coincide.
 9. The methodof claim 8, wherein the controller ignores the output signal of the atleast one sensor where the locations do not substantially coincide. 10.The method of claim 8, further comprising continuously updating anestimated location of the autonomous transport vehicle, with thecontroller, based on a last known verified location of the autonomoustransport vehicle.
 11. The method of claim 10, further comprisingobtaining, with the controller, wheel encoder information from theautonomous transport vehicle for updating the estimated location of theautonomous transport vehicle.
 12. The method of claim 8, furthercomprising aligning transfer arm fingers of the autonomous transportvehicle with spaces located between the reference datums of a respectivestorage shelf based on the determined location of the autonomoustransport vehicle for extending the transfer arm fingers into the spaceswithout contacting the reference datums.
 13. The method of claim 8,further comprising: detecting, with the autonomous transport vehicle,case units located on the storage shelf; and determining, with thecontroller, a position of the autonomous transport vehicle based on thesensed case units.
 14. The method of claim 9, wherein the referencedatums support case units stored on a respective storage shelf.
 15. Amethod comprising: providing at least one vertical lift having at leastone shelf; providing reference datums on at least one wall adjacent theat least one vertical lift, the reference datums being aligned with atleast one predetermined storage position on the at least one shelf;sensing each of the reference datums with at least one sensor of anautonomous transport vehicle and outputting a signal indicating when areference datum is sensed; aligning a payload of the autonomoustransport vehicle with a predetermined storage position on apredetermined shelf of the at least one vertical lift based on adetermined location of the autonomous transport vehicle; determining,with a controller, the determined location of the autonomous transportvehicle relative to the predetermined shelf based on the output signalfrom the at least one sensor; verifying a location of the autonomoustransport vehicle within a storage structure of a storage and retrievalsystem based on at least the output signal from the at least one sensor,and comparing a location of the autonomous transport vehicle at a time areference datum is sensed with a predetermined location of the referencedatum and updating a verified location of the autonomous transportvehicle if the locations substantially coincide.
 16. The method of claim15, wherein the at least one shelf includes at least two item holdinglocations, the method further comprising aligning a transfer arm of theautonomous transport vehicle with one of the at least two item holdinglocations based on the output signal from the at least one sensor. 17.The method of claim 15, further comprising ignoring the out signal fromthe at least one sensor where the locations do not substantiallycoincide.
 18. The method of claim 15, further comprising continuallyupdating an estimated location of the autonomous transport vehicle basedon a last known verified location of the autonomous transport vehicle.19. A storage and retrieval system comprising: at least one verticallift having at least one shelf; at least one wall adjacent the at leastone vertical lift, the wall including reference datums that aresubstantially aligned with at least one storage position on the at leastone shelf; an autonomous transport vehicle including at least one sensorconfigured to sense each of the reference datums and output a signalindicating when a reference datum is sensed, where the autonomoustransport vehicle is configured to align a payload of the autonomoustransport vehicle with a predetermined storage position on apredetermined shelf of the at least one vertical lift based on adetermined location of the autonomous transport vehicle; and acontroller configured to determine the determined location of theautonomous transport vehicle relative to the predetermined storageposition on the predetermined shelf based on the output signal from theat least one sensor; verify a location of the autonomous transportvehicle within a structure of the storage and retrieval system based onat least the output signal; and compare a location of the autonomoustransport vehicle at a time the reference datum is sensed with apredetermined location of the reference datum and update a verifiedlocation of the autonomous transport vehicle if the locationssubstantially coincide.
 20. The storage and retrieval system of claim19, wherein the at least one shelf includes at least two item holdinglocations and the autonomous transport vehicle includes a transfer arm,the autonomous transport vehicle being configured to align the transferarm with one of the at least two item holding locations based on theoutput signal from the at least one sensor.